Compute uncertainty of integral of a component of a TF1

[Wile_E_Coyote]

TH1F variable bin width

Using the "60Codata.txt" file (attached in another post here), try this: { const Bool_t fit_with_fixed_background = kFALSE; // kFALSE or kTRUE const char *filename = "60Codata.txt"; TGraph *g0 = new TGraph(filename, "%lg %lg %*lg"); // X axis = channels g0->SetTitle("g0;Channel number;Energy"); // energy calibration TGraph *g1 = new TGraph(filename, "%lg %*lg %lg"); // X axis = channels g1->SetTitle("g1;Channel number;Counts"); TGraph *g2 = new TGraph(filename, "%*lg %lg %lg");…

Integral Error in Signal

The original example uses “pol1(3)” so there are 2 parameters, but you use “pol2(3)” so you have 3 parameters. That means that you need to change “3, 4” into “3, 5” in all relevant places. In the first macro therein, you also need to add two lines (needed when “fit_with_fixed_background” = “kTRUE”): // ... f1->FixParameter(4, f1->GetParameter(4)); // this line already exists f1->FixParameter(5, f1->GetParameter(5)); // ... f2->FixParameter(4, f2->GetParameter(4)); // this l…

Facing Problem while fitting

The first parameter of “gaus” is the “peak’s height” while the first parameter of “gausn” is the “peak’s area”. In both cases, the second parameter is the “peak’s mean” (i.e. the “peak’s position”). { TGraph *g = new TGraph("eu_gu_1.dat"); // g->Sort(); // just a precaution TF1 *f1 = new TF1("f1", "gausn(0) + pol1(3)", 400., 435.); // linear background f1->SetParameters(14000., 415., 2., 0., 0.); g->Fit("f1", "BR+"); TF1 *f2 = new TF1("f2", "gausn(0) + pol1(3)", 1160., 1200.); f2…